无人机主推进高力能密度永磁电动机关键技术研究

发布时间：2018-03-15 23:30

本文选题：无人机　切入点：主推进永磁电机　出处：《沈阳工业大学》2014年博士论文　论文类型：学位论文

【摘要】：无人机主推进永磁电动机（Main Propulsion Permanent-magnet Motor，简称MPPM）要求具有较高的力能密度（包括功率密度和转矩密度）。同时无人机的飞行工况复杂，分为地面滑跑、起飞爬升、巡航、降落和着陆五个阶段。电机在爬升阶段时力能密度最高，在巡航阶段初期时温升值最高。高力能密度及复杂工况给电机设计和分析带来新问题，本文围绕无人机主推进高力能密度永磁电动机的关键技术展开研究，主要内容如下：根据MPPM对体积和重量的要求以及热负荷达到普通电机5倍的特殊性，本文着重研究了超高力能密度永磁电动机设计方法。在理论上，研究了电机结构参数对电机力能密度影响，对比不同极数、极弧系数、永磁体厚度和电机尺寸对气隙磁密、交直轴电抗和齿槽转矩的影响。对MPPM磁路结构进行了优化设计，分析对比不同隔磁桥、转子外圆的不均匀气隙、永磁体位置对电机的气隙磁密、空载感应电势的影响，给出了MPPM基本优化设计方法。并研究了高频高磁密下MPPM铁心损耗计算方法，重点考虑局部磁滞回环对磁滞损耗的影响，引入设定局部磁滞环的损耗系数K min，给出高电磁负荷下铁心损耗修正系数计算公式。高力能密度将导致电机温升提高，，温升将成为考核主推进电机的重要指标。为提高力能密度MPPM采用开启式结构，通风散热效果好，但冷却空气雷诺数超过10000，流体强紊流特点增加了温度场计算的复杂性。本文针对电动机开启式结构特点，根据流体力学及传热学理论，考虑了高频下的集肤效应对铜耗的影响，建立强风冷却条件下流固耦合物理模型与数学模型，研究了MPPM温度场给出主要固体部件及流体的温度分布，并分析主要部件温升随工况变化曲线。研究给出了不同热负荷状态下，不同爬升时间和爬升角度，MPPM温升特性，从理论和实践上，给出了无人机MPPM热负荷设计范围为30005500A2/cm·mm2，为主推进电动机热负荷设计提供理论参考。 MPPM的超高力能密度，对机械强度和振动提出了更高的要求。本文基于弹性力学理论，建立了主要部件的机械强度计算模型，并分析了不同飞行工况下的应力分布。根据应力分析结构，研究了端盖支撑筋对机壳机械强度的影响，基于模态分析理论对MPPM进行振动特性分析，基于弹性矩阵理论对不同频率下的振型进行了分析。从系统的角度，考虑无人机实际运行中气流波动造成振动的频率，研究MPPM的振动频率和质量参与系数，给出避免发生共振的方法。成功研制MPPM样机，完成首飞试验测试。对样机进行了地面、风洞与飞行试验。样机性能指标：重量20kg，功率25kW，转矩100N·m，力能密度6.25kW·N·m/kg2，远远高于国内水平。飞行试验中温升最高值出现在巡航初期，机壳最高温升89.49K，铁心最高温升105.07K。对比分析MPPM各飞行工况下仿真结果、风洞试验数据和飞行试验数据，证明了理论分析的正确性。
[Abstract]:The main propulsion permanent magnet motor (MPPMM) of UAV requires high force and energy density (including power density and torque density). At the same time, UAV flight conditions are complex, such as ground running, take-off and climb, cruise, etc. The motor has the highest force energy density in the climbing stage and the highest temperature appreciation at the initial stage of cruising. The high power energy density and complex working conditions bring new problems to the design and analysis of the motor. This paper focuses on the key technology of high energy density permanent magnet motor (PMSM) for UAV. The main contents are as follows:. According to the requirement of volume and weight of MPPM and the particularity of heat load reaching 5 times of ordinary motor, the design method of ultra-high energy density permanent magnet motor is studied in this paper. The influence of motor structure parameters on the force and energy density of the motor is studied. The effects of different pole numbers, polar arc coefficients, thickness of permanent magnet and motor size on air gap magnetic density, cross straight axis reactance and tooth slot torque are studied. The MPPM magnetic circuit structure is optimized. The effects of different magnetic isolation bridges, non-uniform air gap of rotor outer circle and permanent magnet position on the airgap magnetic density and no-load induction potential of the motor are analyzed and compared. The basic optimization design method of MPPM is given, and the calculation method of MPPM core loss under high frequency and high magnetic density is studied. The effect of local hysteresis loop on hysteresis loss is considered emphatically. In this paper, the loss coefficient K _ min of local hysteresis loop is introduced, and the calculating formula of core loss correction coefficient under high electromagnetic load is given. The high energy density will lead to the increase of motor temperature rise, and temperature rise will become an important index to evaluate the main push motor. In order to increase the force energy density MPPM, the open structure is adopted, and the ventilation and heat dissipation effect is good. But the Reynolds number of cooled air is more than 10 000, and the characteristics of strong turbulence increase the complexity of temperature field calculation. According to the characteristics of open structure of motor, according to the theory of fluid mechanics and heat transfer, the influence of skin effect at high frequency on copper consumption is considered in this paper. The physical model and mathematical model of fluid-solid coupling under strong wind cooling are established. The temperature distribution of the main solid components and fluids in the MPPM temperature field is studied. The temperature rise curves of main components are analyzed. The temperature rise characteristics of MPPM with different climbing time and angle under different heat loads are given theoretically and practically. The design range of MPPM thermal load for UAV is 30005500A2 / cm 路mm-2, which provides a theoretical reference for the design of thermal load of propulsion motor. The ultra-high force energy density of MPPM has put forward higher requirements for mechanical strength and vibration. Based on the theory of elasticity, the mechanical strength calculation model of main components is established in this paper. According to the stress analysis structure, the influence of the end cap bracing bars on the mechanical strength of the shell is studied, and the vibration characteristics of the MPPM are analyzed based on the modal analysis theory. Based on the elastic matrix theory, the vibration modes at different frequencies are analyzed. From the system point of view, the vibration frequency and mass participation coefficient of the MPPM are studied by considering the frequency of the vibration caused by the airflow fluctuation in the actual operation of the UAV. The method of avoiding resonance is given. The MPPM prototype was successfully developed, and the first flight test was completed. Wind tunnel and flight test. Performance index of prototype: weight 20 kg, power 25 kW, torque 100 N 路m, force and energy density 6.25 kW 路N 路m 路kg 2, which is much higher than domestic level. The maximum temperature rise of the casing is 89.49kg. the maximum temperature rise of the iron core is 105.07k. the correctness of the theoretical analysis is proved by comparing and analyzing the simulation results under the different flight conditions of MPPM, the wind tunnel test data and the flight test data.
【学位授予单位】：沈阳工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM351

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